Probe card with angled probe and wafer testing method using the same

ABSTRACT

A probe card includes a circuit board, a fixing member, and a plurality of probes. The fixing member is fixed on the circuit board and has a through opening therein. The fixing member has opposite first and second sidewalls defining the through opening. Each of the probes includes an arm portion and a tip portion. One end of the arm portion is connected to the circuit board. The tip portion extends from the arm portion. The arm portions of the probes extend in substantially a same direction inclined to a direction perpendicular to the first sidewall of the fixing member in a top view.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/888,757, filed May 31, 2020, now U.S. Pat. No. 11,105,848, issuedAug. 31, 2021, which is a continuation of U.S. patent application Ser.No. 15/058,071, filed Mar. 1, 2016, now U.S. Pat. No. 10,670,654, issuedJun. 2, 2020, which claims priority to Chinese patent application serialnumber 201510982543.2, filed Dec. 24, 2015, all of which are hereinincorporated by reference in their entirety.

BACKGROUND

A wafer acceptable test (WAT) refers to using probes to feed testingsignals into a testing structure of a wafer, and then using a feedbacksignal analysis to understand electrical properties of the wafer,thereby determining if the wafer has defects appearing duringfabrication. In the WAT, a probe card is used to simultaneously testplural chips on the wafer. The probe card includes plural probescorresponding to plural testing pads on the wafer, in which the testingpads are connected to plural devices under test (DUTs) on the wafer.With the increasing chip integrity, contact areas between the tips ofthe probes and the testing pads are greatly shrunk, the affecting theWAT results.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1A and FIG. 1B schematic diagrams showing a wafer testing system inaccordance with some embodiments of the present disclosure.

FIG. 2A is a schematic diagram showing an arrangement of testing pads inaccordance with some embodiments of the present disclosure.

FIG. 2B is a schematic diagram showing a positional relationship betweenprobes and the testing pads in accordance with some embodiments of thepresent disclosure.

FIG. 3A is a schematic cross-sectional view of a probe card inaccordance with some embodiments of the present disclosure.

FIG. 3B is a schematic top view of a fixing member and the probes inaccordance with some embodiments of the present disclosure.

FIG. 3C is a schematic top view of another fixing member and the probesin accordance with certain embodiments of the present disclosure.

FIG. 4 is a schematic side view of the fixing member and the probe inaccordance with some embodiments of the present disclosure.

FIG. 5 is a flow chart showing a method for performing a wafer testingmethod in accordance with some embodiments of the present disclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact.Terms used herein are only used to describe the specific embodiments,which are not used to limit the claims appended herewith. For example,unless limited otherwise, the term “one” or “the” of the single form mayalso represent the plural form. In addition, the present disclosure mayrepeat reference numerals and/or letters in the various examples. Thisrepetition is for the purpose of simplicity and clarity and does not initself dictate a relationship between the various embodiments and/orconfigurations discussed. The spatially relative terms are intended toencompass different orientations of the device in use or operation inaddition to the orientation depicted in the figures. The device may beotherwise oriented (rotated 90 degrees or at other orientations) and thespatially relative descriptors used herein may likewise be interpretedaccordingly.

It will be understood that, although the terms “first”, “second”, etc.,may be used in the claims to describe various elements, these elementsshould not be limited by these terms, and these elements correspondinglydescribed in the embodiments are presented by different referencenumbers. These terms are used to distinguish one element from another.For example, a first element could be termed a second element, and,similarly, a second element could be termed a first element, withoutdeparting from the scope of the embodiments. Further, when a firstelement is described as being “connected” to a second element, suchdescription includes embodiments in which the first and second elementsare directly connected or coupled to each other, and also includesembodiments in which the first and second elements are indirectlyconnected or coupled to each other with one or more other interveningelements in between.

In general, for performing a subsequent dicing operation, a scribe laneis formed in two adjacent chips, and testing pads connected to devicesunder test on a wafer are generally formed in the scribe lane, so as toavoid occupying available surface areas of the wafer. When tips ofprobes contact the testing pads, the tests pads exert a normal force onthe probes, thus deforming the probes and causing the tips of the probesto slide laterally. Such sliding often causes the tips of the probes toslide out of the scribe lane and the testing pads. In addition, the tipsof the probes are formed from a hard electrically conductive materialsuch as titanium nitride, rhodium, tungsten, nickel, etc. When the tipsof the probes contact the testing pads, electrically conductiveparticles often escape therefrom and fall on the testing pads. At thismoment, the sliding of the tips of the probes may bring the electricallyconductive particles to an area between two metal wires adjacent to thescribe lane or the testing pads, thus shorting the metal lines. Theaforementioned problems regarding the tips of the probes escaping thescribe lane and the testing pads and/or the metal lines shorted by theelectrically conductive particles will result in the WAT failure.

In order to prevent the tips of the probes from escaping the scribe laneand the testing pads, widths of the scribe lane and the testing padshave to be maintained above certain values. However, each wafer hasalready had quite a few scribe lanes, and each of the scribe lanesoccupies a certain wafer surface area on which no electrical elementsare allowed to be disposed, and thus it is difficult to increase thewidths of the scribe lanes and the testing pads. Embodiments of thepresent disclosure are directed to deviating a horizontal angle of theprobes entering the testing pads by a proper value, such as about 45degrees, thereby allowing the tips of the probes to have longer slidabledistances on the respective test pads when contacting the testing pads,such that the widths of the scribe lanes and the testing pads do notneed to be increased and even can be decreased. The slidable distancesrefer to the distances within which the tips of the probes would notslide out of the testing pads. Further, the longer slidable distancesalso may lower the possibility of bringing the electrically conductiveparticles to the area between two metal wires. Thus, embodiments of thepresent disclosure area able to promote the success rate of the WAT.

Referring to FIG. 1A and FIG. 1B, FIG. 1A and FIG. 1B schematic diagramsshowing a wafer testing system in accordance with some embodiments ofthe present disclosure. The wafer testing system includes a probe card100, a wafer holder 150, a test head 160 and a tester 170. The probecard 100 includes probes 130, and is disposed below the test head 160 byconnecting to pins 162. The pins 162 may be pogo pins, for example. Thetester 170 is coupled to the test head 160, in which program are storedin the tester 170 for testing various integrated circuit (IC) designs.The probe card 100 is an interface disposed between the test head 160and a DUT (Device Under Test) 146. The probe card 100 is able to converta fixed pin-out capability. For example, the probe card 100 may convertinput or output channels having hardware wirings in the tester 170 to apin arrangement with flexibility, thereby providing a design matchingwith a specific IC design. Thus, the tester 170 may use the same onetest head 160 which is generally very expensive to test various designs.

A wafer 140 is mounted on the wafer holder 150 for being ready toreceive tests, in which testing pads 144 are disposed on a scribe lane142, as shown in FIG. 1B. The testing pads 144 are arranged along a teststraight line and electrically connected to the DUT 146. In someembodiments, plural devices under test (DUTs) 146 and plural scribelanes 142 are formed on the wafer 140, in which the devices under test(DUT) 146 are disposed on the scribe lanes 142. Then, plural elongatedtesting pads 144 arranged along a straight line are disposed on at leastone of the scribe lanes. Thereafter, plural probes 130 are disposed withtheir tips arranged along a straight line, and the tips of the probesare used to contact the respective testing pads 144 for performing anelectrical property measurement on the wafer 140.

When the wafer test is performed, the probes 130 of the probe card 100are first aligned with the testing pads 144 on the wafer 140respectively, and then the probe card 100 is vertically descended or thewafer holder 150 is vertically ascended until the probes 130 contact thetesting pads 144. Meanwhile, the probe card 100 transmits input signalsto the DUTs 146 and then receives output signals outputted from the DUTs146, in which the output signals are in response to the input signals,and the input signals inputted to the probe card 100 and the DUTs 146are generated by the tester 170. Thereafter, the test head 160 transmitsthe output signals to the tester 170, and the tester analyzes the outputsignals to determine the electrical properties of the DUTs 146.

Referring to FIG. 2A, FIG. 2A is a schematic diagram showing anarrangement of the testing pads 144 in accordance with some embodimentsof the present disclosure, in which the testing pads 144 are arrangedalong a test straight line E1 (for example, a Y axis). Each of thetesting pads 144 has a first side 147 and a second side 148 adjacent tothe first side 147, in which the first side 147 is about parallel to thetest straight line E1, and a width (the second side 148) of the testingpad 144 is smaller than a width of the scribe lane 142.

Referring to FIG. 2A and FIG. 2B, FIG. 2B is a schematic diagram showinga positional relationship between the probes 130 and the testing pads144 in accordance with some embodiments of the present disclosure. Asshown in FIG. 2B, each probe 130 includes an arm portion 132 and a tipportion 134 connected to the arm portion 132, wherein the tip portion134 is configured to contact the testing pad 144 on the wafer 140. Thetip portion 134 of the probe 130 is formed from a hard electricallyconductive material such as titanium nitride, rhodium, tungsten, nickel,etc. When contacting and sliding on the testing pad 144, the tip portion134 of the probe 130 generates a scratching effect onto a surface of thetesting pad 144 to remove an oxidized layer on the testing pad 144 dueto being exposed to air, thereby lowering a contact resistance betweenthe testing pad 144 and the probe 130 to testing signal distortion.

When the probes 130 of the probe card 100 are aligned with the testingpads 144 on the wafer 140 respectively, an included angle C1 is formedbetween the test straight line E1 and an extension of a projection lineof the arm portion 132 of each probe 130 projected onto thecorresponding testing pad 144, and the included angle C1 ranges fromabout 40 degrees to about 55 degrees. When contacting the testing pad144, the tip portion 134 of the probe 130 would slide from a contactpoint A1 to another contact portion A2 along a direction L1 parallel tothe arm portion 132. Thus, when the included angle C1 is 45 degrees, thelongest slidable distance of the tip portion 134 sliding on the testingpad 144 is √{square root over (2)}×D1 (D1 is the length of the secondside 148). The longest slidable distance herein is referred to as a“sliding process window”, meaning that the tip portion 134 of the probe130 may slide within the sliding process window without escaping thetesting pad 144. It is known that an arm portion of a conventional probeenters the testing pad 144 along a direction vertical to the first arm147, and thus the longest slidable of a tip portion of the conventionalprobe on the testing pad 144 is D1. Therefore, compared with theconventional probe, the probe 130 in the embodiments of the presentdisclosure has a larger “sliding process window” (a longer slidabledistance), for example, √{square root over (2)}×D1>D1, therebyeffectively preventing the tip portion 134 of the probe 130 fromescaping the testing pad 144, and lowering the possibility of bringingthe electrically conductive particles to the area between two metalwires, thus promoting the success rate of the WAT. In other words,embodiments of the present disclosure deviate the sliding direction ofthe tip portion 134 of the probe 130 from the longer side of the testingpad 144 at the included angle C1 ranging from about 40 degrees to about55 degrees, thereby allowing the tip portion 134 to have a relativelylarge “sliding process window” (slidable distance) on the testing pad144, thus preventing the tip of the probe from escaping the scribe laneor the testing pad due to laterally sliding, further shrinking thewidths of the scribe lane and the testing pad, and increasing wafersurface availability.

Referring to FIG. 3A, FIG. 3B and FIG. 3C, FIG. 3A is a schematiccross-sectional view of the probe card 100 in accordance with someembodiments of the present disclosure; FIG. 3B and FIG. 3C are schematictop views showing the fixing member 120 and the probes 130 in accordancewith some embodiments of the present disclosure; and FIG. 3C is aschematic top view of another fixing member and the probes in accordancewith certain embodiments of the present disclosure. As shown in FIG. 3A,the probe card 100 includes a circuit board 110, a fixing member 120,and the probes 130. The circuit board 110 has a first through opening112, a first surface 114 and a second surface 116 opposite to the firstsurface 114. The fixing member 120 has a second through opening 122, inwhich the fixing member 120 passes through the first through opening 112of the circuit board 110, and is fixed on the second surface 116 of thecircuit board 110. The second through opening 122 has a vertical centralline vertical to a direction parallel to the second surface 116, such asa vertical central line G1 shown in FIG. 3B, or a vertical central lineG2 shown in FIG. 3C. When the probes 130 are aligned with the testingpads 144 respectively, the vertical central lines G1 and G2 are parallelto the test straight line E1 as shown in FIG. 2A and FIG. 2B along whichthe testing pads are arranged. In some embodiments, the fixing member120 has plural grooves 125 extending from edges of the fixing member 120to the second through opening 122. The arm portions 132 of the probes130 are disposed in the grooves 125, and then are sealed by a sealingglue 126. The arm portions 132 of the probes 130 may also be disposed inthe fixing member 120 by other methods, and thus embodiments of thepresent disclosure are not limited thereto. The test head iselectrically connected to the probe 130 through the pin 162 and a jumpwire 118 for inputting signals to the probe 130 or obtaining signalsfrom the probe 130.

The circuit board 110 of the embodiments of the present disclosure maybe a printed circuit board (PCB). Because the probe card 100 is usedunder a high-speed test condition, the material used for forming thecircuit board 110 is quite critical. In some embodiments, a lowdielectric constant material is used for fabricating the circuit board110. The material for forming the circuit board 110 may include an glassreinforced epoxy laminate (such as G10/F4 with a dielectric constant of4.8), a polimid material (with a dielectric constant of 4.2),polycrystalline BaTiO₃ (with a dielectric constant of 3.3-3.9), and anepoxy glass material (with a dielectric constant of about 3.38, forexample).

Each probe 130 includes the arm portion 132 and the tip portion 134connected to the arm portion 132. One end of the arm portion 132 isfixed on the second surface 116 of the circuit board 110, and the otherend of the arm portion 132 passes through a portion of the fixing member120 and is exposed from the second through opening 122. As shown in FIG.3B and FIG. 3C, an includes angle C2 or C3 between the vertical centralline G1 or G2 and an extension of the arm portion 132 ranges from about40 degrees to about 55 degrees, in which the includes angle C2 or C3 isequal to the included angle C1 shown in FIG. 2B. In some embodiments,the second through opening 122 is rectangular (as shown in FIG. 3B),i.e. the second through opening 122 may be a rectangular ring. Incertain embodiments, the second through opening 122 is elliptic (asshown in FIG. 3C), i.e. the second through opening 122 may be anelliptic ring. However, the second through opening 122 of the fixingmember 120 may also be in another shape, as long as the included anglebetween the extension of the arm portion 132 and the vertical centralline ranges between about 40 degrees and 55 degrees. Therefore,embodiments of the present disclosure are not limited thereto.

The above description is directed to the structure of the arm portion132 projected on the wafer 144 (testing pad 140), i.e. the structureviewed on the X-Y plane. The following description describes thestructure of the arm portion 132 directed downwards to the testing pad144 from a sidewall 124 of the second through opening 122 of the fixingmember 120, i.e. the structure viewed on the Z-X plane. However,structures with other angles are also suitable for use in embodiments ofthe present disclosure, and the embodiments of the present disclosureare not limited thereto. Referring to FIG. 4, FIG. 4 is a schematic sideview of the fixing member 120 and the probe 130 in accordance with someembodiments of the present disclosure. As shown in FIG. 4, the armportion 132 is directed downwards to the sidewall 124 of the secondthrough opening, in which an included angle P1 between the arm portion132 and the sidewall is about 84 degrees, and an included angle P2between the arm portion 132 and a horizontal line H1 is about 6 degrees.One end of the tip portion 134 is connected to the arm portion 132, andthe other end thereof is directed downwards. An included angle P3between the tip portion 134 and the arm portion 132 is about 104degrees, and an included angle P4 between the tip portion 134 and avertical line H2 is about 7 degrees.

Hereinafter, a wafer testing method is explained according toembodiments of the present disclosure. Referring to FIG. 5, FIG. 5 is aflow chart showing a method for performing a wafer testing method inaccordance with some embodiments of the present disclosure. As shown inFIG. 2A and FIG. 5, at first, plural testing pads 144 are formed along atest straight line E1 on a wafer 140 (operation 210), in which each ofthe testing pads 144 has a first side 147 and a second side 148 adjacentto the first side 147. Then, as shown in FIG. 1A and FIG. 5, the wafer140 is placed on a wafer holder 150 (operation 220). As shown in FIG. 2Band FIG. 5, plural probes 130 are fabricated (operation 230), in whicheach probe 130 includes an arm portion 132 and a tip portion 134connected to the arm portion 132, in which the operation 230 offabricating the probes 130 forms an included angle C1 between the teststraight line E1 and an extension of a projection line of the armportion 132 of each probe 130 onto the wafer 140, and the included angleC1 ranges substantially from 40 degrees to 55 degrees. Thereafter,operation 240 is performed to enable the tip portions 134 of the probes130 to contact the testing pads 144. When contacting the testing pads144, the tip portions 134 slide from the first side 147 of each testingpad 144 towards a direction L1, in which the direction L1 has theincluded angle C1 with the first side 147 of each testing pad 144. Insome embodiments, the operation 240 is performed under a high-speed testcondition.

It can be known from the above that embodiments of the presentdisclosure have the following advantages. Because the included anglebetween the test straight line and the extension of the projection lineof the arm portion of each probe onto the wafer ranges from about 40degrees to about 55 degrees, the probe in the embodiments of the presentdisclosure has a larger “sliding process window” (a longer slidabledistance), thereby effectively preventing the tip portion of the probefrom escaping the testing pad, and lowering the possibility of bringingthe electrically conductive particles to the area between two metalwires, thus promoting the success rate of the WAT, further shrinking thewidths of the scribe lane and the testing pad, and increasing wafersurface availability.

In accordance with some embodiments, a probe card includes a circuitboard having a through opening therein. A fixing member is at leastpartially in the through opening of the circuit board and has a throughopening therein. The through opening of the fixing member is defined atleast partially by opposite first and second sidewalls of the fixingmember. A plurality of probes each includes an arm portion and a tipportion. One end of the arm portion is connected to the circuit board.The arm portion extends through the first sidewall of the fixing memberinto the through opening of the fixing member. The arm portion is angledwith respect to a direction perpendicular to the first sidewall of thefixing member when viewed from above. The tip portion extends from thearm portion. The second sidewall of the fixing member is free of probes.

In accordance with some embodiments, a probe card includes a circuitboard having a through opening therein. A fixing member is at leastpartially in the through opening of the circuit board and has a throughopening therein. The through opening of the fixing member is defined atleast partially by adjacent first and second sidewalls of the fixingmember. A plurality of probes each includes an arm portion and a tipportion. One end of the arm portion is connected to the circuit board.The arm portion extends through the first sidewall of the fixing memberinto the through opening of the fixing member. The arm portion is angledtoward the second sidewall of the fixing member when viewed from above.The tip portion extends from the arm portion. The second sidewall of thefixing member is free of probes.

In accordance with some embodiments, a method includes placing a waferon a wafer holder. The wafer has a plurality of testing pads thereon.The testing pads of the wafer are arranged along a first direction. Aprobe card is moved toward the wafer. The probe card includes a circuitboard having a through opening therein. A fixing member is at leastpartially in the through opening of the circuit board and has a throughopening therein. The through opening of the fixing member is defined atleast partially by opposite first and second sidewalls. A plurality ofprobes each includes an arm portion and a tip portion. One end of thearm portion is connected to the circuit board. The arm portion extendsthrough the first sidewall of the fixing member into the through openingof the fixing member. The tip portion extends from the arm portion. Thesecond sidewall of the fixing member is free of probes. Moving the probecard toward the wafer is performed such that each of the tip portions ofthe probes slides on a corresponding one of the testing pads of thewafer along a second direction that is angled with respect to a thirddirection perpendicular to the first direction.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A probe card, comprising: a circuit board; afixing member fixed on the circuit board and having a through openingtherein, wherein the fixing member has opposite first and secondsidewalls defining the through opening; and a plurality of probes, eachof the probes comprising: an arm portion, wherein one end of the armportion is connected to the circuit board; and a tip portion extendingfrom the arm portion, wherein the arm portions of the probes extend insubstantially a same direction inclined to a direction perpendicular tothe first sidewall of the fixing member in a top view.
 2. The probe cardof claim 1, wherein the second sidewall of the fixing member is free ofprobes.
 3. The probe card of claim 1, wherein the fixing member furtherhas opposite third and fourth sidewalls defining the through opening andconnected to the first and second sidewalls, and a length of the firstsidewall is greater than a length of the third sidewall in the top view.4. The probe card of claim 3, wherein the arm portions of the probesextend in the same direction further inclined to a directionperpendicular to the third sidewall of the fixing member in the topview.
 5. The probe card of claim 1, wherein a top surface of the fixingmember is higher than a bottom surface of the circuit board.
 6. Theprobe card of claim 1, wherein the fixing member is in contact with abottom surface of the circuit board.
 7. The probe card of claim 1,wherein an arrangement of the probes is asymmetric with respect to acentral line of the first sidewall of the fixing member in the top view.8. A probe card, comprising: a fixing member having opposite first andsecond sidewalls defining a through opening therebetween; a circuitboard laterally surrounding a top portion of the fixing member such thata bottom portion of the fixing member is below a bottom surface of thecircuit board; and a plurality of probes connected to the circuit board,wherein each of the probes comprises: an arm portion extending from thecircuit board, through the fixing member, to the through opening of thefixing member; and a tip portion connected to the arm portion, whereinextending directions of the tip portions of the probes are substantiallythe same and are inclined to a direction perpendicular to the firstsidewall of the fixing member in a top view.
 9. The probe card of claim8, wherein a third sidewall of the fixing member extends from a firstedge of the first sidewall of the fixing member to a first edge of thesecond sidewall of the fixing member, the through opening of the fixingmember is defined at least partially by the first, second, and thirdsidewalls of the fixing member, and the third sidewall of the fixingmember is free of probes.
 10. The probe card of claim 9, wherein afourth sidewall of the fixing member extends from a second edge of thefirst sidewall of the fixing member to a second edge of the secondsidewall of the fixing member, the through opening of the fixing memberis defined at least partially by the first, second, third, and fourthsidewalls of the fixing member, and the fourth sidewall of the fixingmember is free of probes.
 11. The probe card of claim 10, wherein eachof the arm portions of the probes is angled away from the fourthsidewall of the fixing member when viewed from above.
 12. The probe cardof claim 8, wherein the tip portions of the probes are substantiallyparallel with each other.
 13. The probe card of claim 8, wherein thethrough opening of the fixing member is substantially rectangular whenviewed from above.
 14. The probe card of claim 8, wherein the firstsidewall of the fixing member is substantially parallel to the secondsidewall of the fixing member.
 15. A method comprising: placing a waferon a wafer holder, wherein the wafer has a plurality of testing pads,and the plurality of testing pads of the wafer are arranged along afirst direction; moving a probe card toward the wafer, the probe cardcomprising: a circuit board; a fixing member having a through openingtherein, wherein the through opening of the fixing member is defined atleast partially by opposite first and second sidewalls; and a pluralityof probes, each of the probes comprising: an arm portion, wherein oneend of the arm portion is connected to the circuit board; and a tipportion extending from the arm portion; and aligning the tip portions ofthe probes with the plurality of testing pads such that sidewalls of theplurality of testing pads are substantially parallel to the firstsidewall of the fixing member and are oblique to extending directions ofthe arm portions of the probes.
 16. The method of claim 15, furthercomprising after aligning the tip portions of the probes with theplurality of testing pads, moving the probes along the extendingdirections of the arm portions of the probes.
 17. The method of claim15, wherein moving the probe card toward the wafer is performed suchthat each of the tip portions of the probes crosses a central axis ofeach of the plurality of testing pads.
 18. The method of claim 15,wherein an angle between one of the sidewalls of the plurality oftesting pads and one of the extending directions of the arm portions ofthe probes ranges from about 40 degrees to about 55 degrees.
 19. Themethod of claim 15, wherein the second sidewall of the fixing member isfree of probes.
 20. The method of claim 15, wherein the through openingof the fixing member is substantially rectangular when viewed fromabove.